What is an entity in computer science?

An entity in computer science refers to a Unique and identifiable information object. These can be both real and abstract objects. The term "entity" comes from Latin and means "something that exists". In the IT industry, the term is often used in areas such as database management, programming and Search engines is used. Entities are represented by a combination of attributes and relationships and can be represented graphically in entity-relationship models. Together with entity types, attributes and relationships between entities, they are important components of data modelling.

Types and representation

An entity is usually represented by a Combination of attributes and relationships displayed. Attributes describe the properties of an entity, such as the first name, surname or place of residence of a person. The actual values of these attributes would be, for example, first name "Max" and last name "Mustermann". The interaction of attributes and attribute values creates information about the properties of an entity. The Entity typealso referred to as entity class, describes a specific group of entities. For example, a person with the attribute values "Max Mustermann" can belong to the entity type "customer" or "patient".

There are different types of entities used in computer science. One of them is the weak entitythat is dependent on another entity. An example of this is an order line that depends on an order.

Another type of entity is the strong entitythat is independent of other entities. An example of this is a customer that is not dependent on an order.

The Entity Relationship Model

The entity-relationship model is a widely used instrument in the generation of a data model for a Database. It abstracts the types of entities, their attributes and the relationships between them to create a graphical entity-relationship diagram that forms the basis for the actual data model. The model is composed of the diagram and the description of the elements used.

Relational databases use the entity-relationship model by equating entity types with tables and table rows with individual entities. The model is used in the conceptual phase of database development, as well as in the implementation of relational databases.

The Entity Relationship Model was introduced by Peter Chen in 1976 and has been an established de facto standard for data modelling ever since. It is an important part of database development and helps developers create a clear and understandable data model that captures the properties, attributes and relationships of entities in a database.

Examples for entities

An example of an entity in a Online shop application is a product. The product entity has attributes such as product name, description, price and stock. It also has relationships with other entities such as category and manufacturer.

An example of an entity in a Human Resources Management Application is a staff member. The employee entity has attributes such as first name, last name, address, date of birth and position. It also has relationships with other entities such as department and supervisor.

An example of an entity in a Financial management system is an account. The account entity has attributes such as account number, account name, current balance and currency. It also has relationships with other entities such as customer and transactions.